Air handling systems such as air conditioning systems typically have a condensate drain pan to collect condensate.
Often removal of the condensate requires pumping the condensate from the condensation drain pan. Commonly, a drain pan system includes a sensor placed in the drain pan to measure the level of the condensation therein. When the condensate level reaches a predetermined level, the sensor generates a signal sent to a sensor switching circuit to activate the pump or stop operation of the compressor.
HVAC systems know as mini-split systems present a particularly troublesome challenge. Mini-split systems comprise of two basic units—a compressor and multiple air handlers. The air handler is typically mounted on the wall in the space to be cooled. These air handlers are designed to be compact resulting in limited space for an overflow switch and condensate sensor. Specifically, systems use refrigerant lines together power and control wiring to connect the outdoor compressor to the individual indoor air handlers. The technology, developed in the 1950s, is called split-ductless or mini-split and is the primary method for conditioning spaces within a home or commercial building in countries around the world. Mini-split systems allow each space with an indoor air-handler unit to be controlled independently from other rooms, thus providing individualized comfort control within a home.
In such mini-split systems, the compressor is connected to existing house voltage and supplies voltage to the air handlers.
In addition, a communications link is used to coordinate the operation of the two basic units. As a result, any electronics that would utilize the power supply has the potential of disrupting the communication link. Thus, any effort to provide a condensate removal system would require an electrically isolated battery powered system.
In order to shut down the highly integrated electro-mechanical mini-split system, a condensate control system can be tapped into a commonly found thermistor used to measure the evaporator temperature forming part of mini-split control loop. As designed, if the thermistor is broken or indicates a bad reading the compressor is shut down. This thermistor can be used to open the circuit when excess condensate is sensed in the condensate drain pan to shut down the compressor.
The present invention employs a solid state relay or switch to control the thermistor without intruding or compromising the integrity of the power supply or communication link of existing mini-split systems.